Comparative Analysis of Nasopharyngeal Mast Cells Across Pediatric Viral Infections 2309423

Abstract Introduction Mast cells are long-lived, myeloid-lineage immune cells enriched at mucosal surfaces, where they reside to sense and respond to foreign antigens. While well studied in allergic disease, their roles in viral immunity remain incompletely defined. By defining the cellular states of mast cells in response to rhinovirus (RV), respiratory syncytial virus (RSV), and SARS-CoV-2, we aimed to evaluate the hypothesis that mast cells in the nasopharyngeal mucosa adopt virus-specific inflammatory states during pediatric upper respiratory tract infection (URTI). Methods Nasopharyngeal swabs were collected from pediatric patients infected with RV, RSV, or SARS-CoV-2, and uninfected controls (UC) at Boston Children’s Hospital. Single-cell RNA sequencing (10X Genomics) was performed on swab-dissociated cell suspensions, followed by integrated analysis to identify mast cell subsets and compare virus-associated transcriptional programs. Results 684 mast cells were isolated from a dataset of approximately 290,000 cells from 97 participants. Unsupervised clustering revealed four distinct mast cell states: 1) Resting, 2) Inflammatory, 3) Interferon-stimulated gene-positive (ISG+, TNF-), and 4) ISG+, TNF+. Across all viral infections, mast cell frequency was increased; however, discrete cell states displayed virus-specific associations. SARS-CoV-2 mast cells were predominantly defined by the Inflammatory state; RV by the ISG+, TNF- state; RSV by the ISG+, TNF+ state; and UCs by the Resting state. Gene-set enrichment analysis reflected these virus-specific differences. Conclusion These data suggest that mast cells mount unique, virus-specific inflammatory responses in the nasopharyngeal mucosa during pediatric viral URTI and thus may be a future target for modulation of virus-specific mucosal inflammation in children. Funding Source NIH R01 DE031928 Topic Categories Mucosal and Regional Immunology (MUC)